As raw materials of a medical glass container, such as a medical vial, borosilicate glass excellent in chemical durability has been used in many cases. The borosilicate glass is molded into a glass tube to be used as a raw material of the medical glass container. Such a glass tube includes Type I, Class B having an expansion coefficient (×10−7/K) of 48 or more and 56 or less (hereinafter also referred to as Type IB) and Type I, Class A having an expansion coefficient (×10−7/K) of 32 or more and 33 or less (hereinafter also referred to as Type IA) described in Non-Patent Literature 1 (Non-Patent Literature 1). A medical vial manufactured using glass having a low expansion coefficient as the raw material is hard to cause breakage due to rapid temperature changes. Therefore, a Type IA borosilicate glass tube having a low expansion coefficient has been used as the raw material of the medical vial which is required to have durability against rapid temperature changes, such as freezing/thawing.
In order to manufacture a medical vial from the borosilicate glass tube, a mouth portion and a bottom portion of the vial are molded in the glass tube by heating with high temperature flames. Ina process in which the bottom portion is molded from the glass tube, alkaline components volatilized from the glass tube due to the heating of the glass tube condense particularly on the inner surface near the bottom portion, so that a deteriorated layer is formed. The alkaline components are eluted from such a deteriorated layer into a pharmaceutical agent and the like in the vial. To address the problem, the alkaline component of elution standard is established in European Pharmacopoeia and United States Pharmacopeia and ISO4802-1 or ISO4802-2.
As a method for reducing the elution of alkaline components, an ammonium sulfate treatment method including causing alkaline components and sulfate present in a deteriorated layer to react with each other to generate sodium sulfate (Na2SO4), and then removing the sodium sulfate by washing with water and a chemical vapor deposition (CVD method) including covering a vial inner surface with a silica (SiO2) thin film are known (Patent Literature 1). Moreover, it is known that a deteriorated layer generated on the inner surface of a vial is subjected to fire blasting with an oxygen-gas flame by a point burner while rotating the vial molded from a glass tube, whereby the deteriorated layer is removed, so that the elution of alkaline components is reduced (Patent Literatures 2 and 3).